Found in old American documentation, this circuit is current as it uses the 555 to modulate an infrared LED. Pulses are set by R1.
In this circuit the photo-transistor signal is amplified by a Darlington step and then applied to a...
The purpose of this circuit of an American publication from the 70s is to move the signal from an...
This 80's circuit can be implemented with modern equivalent FETs with lower on resistance. The...